System for uplink scheduling packet based data traffic in wireless system

ABSTRACT

A system for allocating bandwidth resources among various mobile stations which are wirelessly connected to a base station. The length of the data queue in each mobile station is determined and information regarding that length is placed in a field in the outgoing data packet. When it is received in the base station, this field is decoded and the queue length information used to allocate bandwidth resources among the mobile station connections. This allows a very quick response to data queue lengths and accordingly better service.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] This invention relates generally to a system for allocatingresources for data streams and more particularly to a system forallocating transmission resources in a wireless system where the dataincludes an indication of its own resource needs.

[0003] 2. Description of the Background

[0004] In networks and other arrangements, a situation often developswhere a limited number of resources, such as bandwidth must be sharedamong a plurality of links. In particular, in a wireless type network, anumber of mobile stations may be connected to a base station by wirelessconnections. Each base station may have only a limited number ofchannels to make these connections. Since many such mobile devices nowutilize more than basic voice data, the amount of data which flows canvary substantially. Thus in addition to voice communications, wirelessdevices may include real time video, e-mail, web based information, etc.In order to fairly allocate the resources available, it is necessary forthe base station to make some judgment as to which mobile stations canutilize the channels, and for how long.

[0005] The simplest arrangement, and one used largely in the past forvoice data, is merely to dedicate a single channel for a single mobilestation as long as it is connected. Only the assigned mobile station canuse the channel. Depending on the original request, it is possible toassign more than a single channel but these multiple channels remaindedicated to that mobile station until the connection is terminated. Noinformation is shared about the instantaneous amount of data waiting inthe mobile station.

[0006] Another manner of handling the situation is to utilize a pollingscheme where the base station polls each mobile station to learn thestatus of the data queue in each mobile station.

[0007] This allows the base station to determine how to share thebandwidth resources among the different mobile stations. Thus, whenpolled the mobile station can send a response indicating whether it hasdata to transmit. For example, in a global system for mobile devices(GSM) time division multiple access (TDMA) system, the transmissionopportunity for a mobile station is granted n frames after the basestation receives the polling response from the mobile station, where nis the number of frames required to transmit a data block in thechannel. Thus, there is a delay of multiple frames after polling, beforean adjustment can be made.

[0008] Unfortunately, real time traffic such as video conference hasunpredictable fluctuations in the data rate. Thus, any delay inadjusting the resources may mean that a link to a mobile station may notalways have data in its transmission queue.

[0009] Since a dedicated channel assignment scheme does not allow anyother mobile stations to use the channel when the assigned mobilestation uplink queue is empty, the bandwidth assigned will not be used,which lowers overall spectrum efficiency. This leads to poor bandwidthutilization which will only get worse as the number of connections inthe system increases. Also, during high data rate periods, the number ofreal time packets waiting in the uplink queue will increase. Due to thelimited bandwidth share assigned to the mobile station, packetcongestion can occur and an increasing number of packets can exceedtheir delay requirements therefore decreasing the quality of serviceperceived by the end user. While the polling scheme is more efficientthan a dedicated channel assignment scheme from the perspective ofbandwidth utilization, some bandwidth is still wasted because the mobilestation cannot send actual data when sending a polled response. Aspolling becomes more frequency, more bandwidth is wasted. Further,additional delay is introduced because the packet has to wait while thepoll is received and answered. Thus, the delay will further slow downtransmission and counteracts any benefits gained by the polling.

SUMMARY OF THE INVENTION

[0010] Accordingly, the present invention provides a system forallocating transmission resources between the base station and a seriesof mobile stations.

[0011] The present invention also provides a method for allocatingresources based on the amount of data waiting in a queue in each mobilestation.

[0012] The present invention also provides a system for allocatingbandwidth resources between a plurality of mobile stations and a singlebase station in a wireless network.

[0013] The present invention further provides a method for allocatingbandwidth resources between a plurality of mobile stations and a singlebase station in a wireless network.

[0014] The present invention further provides a system for transmittinginformation concerning the amount of data in a queue so that resourcesmay be allocated appropriately for the most efficient use of theresources.

[0015] The present invention still further provides a method fortransmitting information regarding the amount of data stored in a queuein a mobile station in a wireless network.

[0016] Briefly, this invention is achieved by using a plurality of bitsin each data segment to describe the size of one of the queues in thatmobile station. Once this is received in the base station, additionalresources can be allocated if necessary.

[0017] A more complete appreciation of the invention and many of theattendant advantages thereof will be readily obtained as the samebecomes better understood by reference to the following detaileddescription when considered in connection with the accompanyingdrawings, wherein:

DETAILED DESCRIPTION

[0018]FIG. 1 is a schematic diagram showing the arrangement of thepresent system;

[0019]FIG. 2 is a block diagram showing a mobile station according tothe present invention;

[0020]FIG. 3 is a block diagram showing a base station according to thepresent invention;

[0021]FIG. 4 is a flow chart showing the method of determining the queuelength; and

[0022]FIG. 5 is a flowchart showing the method of utilizing theinformation.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] Referring now to the drawings, wherein like reference numeralsdesignate identical or corresponding parts throughout the several viewsand more particularly to FIG. 1 thereof, wherein the wireless system 10is shown as including a base station 12 and mobile stations 14. Asindicated in the figure, the individual mobile stations may be connectedto the base station by wireless connections. Since the base station isallowed to use only a certain range of frequencies, there is limit tothe bandwidth available to the mobile stations. Since this resource islimited, it is necessary to allocate this bandwidth so that the greatestamount of data can be moved in the shortest time. This improves thequality of service and avoids unnecessary delay for the users.

[0024] The present invention improves on previous schemes by allocatingthe bandwidth among the various mobile stations which are currentlyconnected to the base station. In order to do this, it is necessary forthe base station to have some idea of the amount of data in the queue inthe individual mobile stations. Prior art systems do not provide forthis information to be given to the base station, nor are the resourcesallocated in real time based on this information.

[0025] Of course, each mobile station can have more than one connectionfor different types of data (voice, e-mail, video, etc). It is evenpossible to have multiple connections of a single type of data. Eachtype of data is handled separately.

[0026] Data which is sent from the mobile stations to the base stationis arranged in blocks according to the protocol governing the apparatus.Of course, different data types may include blocks simultaneously. Thus,such blocks include not only the data itself, but identificationinformation and other bits which may be used for other purposes such aserror checking, etc. In particular, in the enhanced general packet dataradio services system (EGPRS), there is provided a field of four bitswhich are known as the countdown value CV of the block. Under thecurrent scheme, the bandwidth allocated to the mobile station is fixedand these four bits indicate the queue length of that mobile station. Inparticular, it indicates the number of data blocks in the queue as longat it is less than 16. This provides an estimate of when the currentdata transfer will be finished. However, this is not used in any mannerto control the resources available. Different data types from the samemobile station utilize different queues. Thus, the voice is handledseparately from the video, etc. Each queue has its own CV.

[0027] In the present arrangement, these four bits instead provide anindication of the data in the queue so that the base station maydetermine if additional resources are necessary in order to move thedata at the optimum speed. Each service type (e.g. voice, video, email)will use a separate queue in the mobile station and each queue will havean associated CV. While the particular data included in the four bits ofthe CV may have various different meanings, the preferred arrangement isto let the values of 0-8 indicate the number of data segments in thequeue. These values will indicate a queue length if it is less than orequal to the segment rate. This segment rate is the parameter which isestablished between the mobile station and the base station during theset up phase. If the queue length exceeds the segment rate, the valuesof 9-15 in the four bit field indicate the additional bandwidth which isrequired in order to meet the delay/rate requirement of the packet.

[0028] Thus, as the individual packets are sent from the mobile stationto the base station, the base station examines this four bit field andnotes the situation in the corresponding queue at that mobile station.If additional resources are necessary, the base station will allocateadditional bandwidth to that connection so that the data stored in thequeue will move faster. This of course assumes that sufficient resourcesare available to add resources to that connection. Clearly, the basestation must consider all of the requests of all of the connectionsbefore allocating these resources. Since the four bit field is sent withevery packet, the base station is constantly updated as to the situationin each mobile station. Accordingly, it can closely monitor thesituation and adjust it over a very short time period to improve theutilization of its resources. This arrangement is much faster than thepolling scheme because the information is provided in each packetwithout wasting bandwidth for the polling communications. Further, thepresent arrangement utilizes a four bit field which is already presentaccording to the current protocols. It is only necessary to provide thatthe base station and mobile station each have a proper system for addingthe data and using the data.

[0029]FIG. 2 shows a block diagram of a mobile station 14. While thestation is shown as including a number of circuits, in fact, thesefunctions could also be performed by software in a processor. A datagenerator 20 produces the data which is to be transmitted by the mobilestation. This can include any of the normal devices which are utilizedin a mobile station to produce data including a microphone to producevoice data, a keyboard to produce alpha numeric data, a camera forproducing video data, etc. The specific type of data generation is notcritical to the operation of the present invention. However, no matterwhat type of data is produced, it is sent to a data queue 22 to awaitits transmission. A queue length measuring device 24 observes the amountof data in the queue and determines the queue length. This queue lengthinformation is sent to encoder 26 which determines the four bit code toplace in the field based on the length of the queue. Thus, in thepreferred system described above, if the queue is less than the segmentrate, a value between zero and eight is encoded and if the queue lengthis greater than the segment rate a value between nine and fifteen isencoded. The exact value in either of these ranges depends on the lengthof the queue. Other schemes of encoding could easily be used also merelyby changing the encoding scheme. Thus, it would be possible to use aqueue length value only if preferred or only a value for additionalbandwidth. Other values could also be utilized as long as they relate insome manner to the length of the queue and can be utilized in the basestation to allocate the bandwidth appropriately. Obviously, someencoding schemes will provide better information and allow for moreappropriate allocation of resources.

[0030] Once the four bit code has been generated, it is added to thedata block in a combiner 28. Thus, the code is added to the data blockonly when it reaches the front of the line in the queue so that the mostupdated information about the length of the queue can be given.Alternatively, the code can be added based on the length of the queuewhen the data block enters the queue, but this information would beslightly less fresh. In this alternative arrangement, the combiner wouldmake the combination as the data enters the queue. In either case, whenthe packet is ready for transmission, it is sent to transmitter 30 so asto be connected to the base station through antenna 32.

[0031] As shown in FIG. 3, base station 12 includes an antenna 34 andreceiver 36 which receive the packet transmitted from antenna 32. Ofcourse, this antenna and receiver are in communication with severalmobile stations at the same time. For simplicity of discussion, it will,however, be discussed as if only a single mobile station were connectedat a time. The receiver 36 forwards the received data onto signalprocessor 38 for further handling of the data and eventual connection ofthe data to output lines 40. However, decoder 42 looks at the datasignal and determines the code in the four bit field which representsthe queue length information. This decoder then provides the queuelength information for the associated mobile station to the resourcecontroller 44. The resource controller determines the situation in thedata queue in the associated mobile station and determines whetheradditional resources should be allocated to that mobile stationconnection and if the resources are available. The controller obviouslymust prioritize the needs of the various stations in view of theresources available and distribute them in the most effective manner.This controller then determines the various bandwidth resourcesavailable for each mobile station and controls the receiver to arrangethis. The actual decision process as to how to allocate the resourcesbased on this information may vary. It may take into consideration theimportance of the information, its time sensitivity, the importance ofthe particular user, or other factors in addition to the amount of datain each station. However, the allocation should be such as to give thebest quality of service to as many stations as possible. However, thesimple manner of making this choice is merely to allocate the mostresources to the station with the largest queue without lowering thesegment rate which has been guaranteed. Just as in the mobile stations,the various circuitry indicated for the base station may actually behardwired devices or may be programmed functions of a processor.

[0032] In a preferable system, the real time data packet is split intodata segments for the purpose of transmission. In packet cellularsystems, data segments correspond to a radio link control/multipleaccess control (RLC/MAC) block, which is a layer 2 data block. Each datasegment is transmitted individually over the transmission media when theopportunity is granted. A transmission opportunity is defined as anymethod used to transport a data segment on the transmission media. Forexample, in a time division multiple access system (TDMA) thetransmission opportunity is a time slot and in a wideband code divisionmultiple access (WCDMA) system it is the utilization of a unique WALSHcode in a radio frame. The radio frame is shared by multiple users usingdifferent WALSH codes. The base station schedules the data packets andorganizes the transmission opportunities for current user traffic. Thepresent invention presents a model that will help the scheduling in thebase station to provide for optimum service for all users in the uplinkdirection. Traffic information is sent in each block in the uplink. Byincluding this information in one field of the block, real timeinformation is provided to enable better scheduling.

[0033] While this arrangement has been described in terms of a wirelessconnection between a mobile station and a base station, it could also beapplied to other systems where the connections are made by wire, fiberoptic cable, etc. The only requirement is that the queue lengthinformation can be sent with the data block and that the resources canbe allocated based on this data.

[0034] The method of operation of this system is seen in the flow chartsof FIGS. 4 and 5. FIG. 4 relates to the method of determining the queuelength and encoding the four bit field in the mobile station. In step100, the data queue length is determined. In step 102 the determinedlength is converted to a four bit code which is related to the queuelength. This code is inserted in the data packet in step 104. The packetis then transmitted in step 106.

[0035]FIG. 5 shows the method of utilizing this information in the basestation. In step 110, the signal from a particular mobile station isreceived. In step 112 the data is forwarded. In step 114 a decoderreceives the encoded four bit field and decodes it. In step 116 theresource controller receives the decoded information and determines thelength of the queue. In step 118, the resources are based on thisinformation.

[0036] Numerous additional modifications and various of the presentinvention are possible in light of the above teachings. It is thereforeto be understood that within the scope of the appended claims, theinvention may be practiced otherwise than is specifically describedherein.

1. A method of controlling communication resources in a transmissionfrom a first network element to a second network element, where thecommunication resources are allocated by a controller, comprising:monitoring an indication of future need of communication resources insaid first network element; sending the indication from the firstnetwork element to the controller; controlling the communicationresources between the first network element and the second networkelement based on this indication.
 2. The method according to claim 1,wherein the first network element is connected to the controller by wayof the second network element.
 3. The method according to claim 1,wherein the indication includes information about a transmit buffer ofthe first network element.
 4. The method according to claim 1, whereinthe indication includes information on the additional resources neededfor said first network element.
 5. The method according to claim 3,wherein the indication includes a quantization scheme whose valuescorrespond to predefined amounts of resources.
 6. The method accordingto claim 4, wherein the indication includes information about a transmitbuffer of the first network element.
 7. A method according to claim 1,wherein the first network element is a mobile station and the secondnetwork element is a base station of a wireless communication network.8. A system for controlling communication resources in a network,comprising: a plurality of first stations; a second station connected tosaid plurality of first stations through a plurality of communicationlinks; a controller for controlling the allocation of said communicationresources among said links; said allocation being performed inaccordance with information transmitted from said first stations whichindicates a need for communication resources.
 9. The system according toclaim 8, wherein said controller is part of said base station.
 10. Thesystem according to claim 8, wherein said first stations are mobilestations in a wireless network.
 11. The system according to claim 8,wherein each of said plurality of first stations includes: a datagenerator; a data queue; an encoder for generating a code representativeof the length of the data queue; a transmitter for transmitting saiddata with said code included therein as a field.
 12. The systemaccording to claim 8, wherein said base station includes a receiver forreceiving a transmission and producing data; a decoder for decoding afield of said data and producing an indication of the data queue in anassociated first station; wherein said controller receives saidinformation from said decoder and allocates communication resources inaccordance therewith.
 13. The system according to claim 8, wherein saidindication is provided for each data block transmitted.